Torsion rod type picking mechanism for a projectile loom

Abstract

The picking mechanism has a torsion rod whose zero position is adjustable by an adjusting lever and an adjusting drive. A rigid wedge-shaped intermediate member movable by the adjusting drive is disposed between a sliding surface of the adjusting lever and a stationary sliding surface. Movement of the intermediate member produces a pivoting movement of the adjusting lever to alter the zero position. The intermediate member transfers a force exerted by the adjusting lever on to the stationary sliding surface.

What is claimed is: 
     
       1. A picking mechanism for a projectile loom comprising a torsion rod having a longitudinal axis;   an adjusting lever secured to said rod for rotating said rod about said axis relative to a zero position of said rod; and   an adjusting mechanism for pivoting said lever about said axis to vary said zero position of said rod, said mechanism including a rigid intermediate member disposed between said adjusting lever and a stationary surface and a drive for moving said member relative to said lever to effect a corresponding pivotal movement of said adjusting lever while transferring a force from said lever onto said stationary surface.   
     
     
       2. A picking mechanism as set forth in claim 1 wherein said intermediate member has a first sliding surface facing and slidably receiving said lever and a second sliding surface facing and slidably engaging said stationary surface. 
     
     
       3. A picking mechanism as set forth in claim 2 wherein said intermediate member is wedge-shaped and said drive moves said member in translation. 
     
     
       4. A picking mechanism as set forth in claim 3 which further comprises a guide member connected to said wedge-shaped intermediate member for guiding said lever therebetween to prevent disengagement of said lever from said intermediate member. 
     
     
       5. A picking mechanism as set forth in claim 1 which further comprises a slide block rotatably mounted in said lever and slidably contacting said intermediate member to transfer said force therebetween. 
     
     
       6. A picking mechanism as set forth claim 1 wherein said intermediate member is rotatably mounted on a second axis perpendicular to said lever and has a screwthread thereon and said drive includes a stationary screwthreaded surface receiving said screwthread of said intermediate member to effect movement of said member along said second axis in response to rotation of said member. 
     
     
       7. A picking mechanism as set forth in claim 6 wherein said drive includes a motor for rotating said intermediate member about said second axis. 
     
     
       8. A picking mechanism as set forth in claim 1 wherein said intermediate member is rotatably mounted on a second axis parallel to said longitudinal axis of said rod and has a curvilinear surface of non-circular shape contacting said lever for pivoting said lever in response to rotation of said member. 
     
     
       9. A picking mechanism as set forth in claim 8 wherein said curvilinear surface is a spiral surface. 
     
     
       10. A picking mechanism as set forth in claim 1 wherein said drive includes a stepping motor. 
     
     
       11. A picking mechanism as set forth in claim 1 which further comprises at least a pair of sensors for monitoring the position of said lever and emitting a responsive signal for activating said drive to pivot said lever. 
     
     
       12. A picking mechanism as set forth in claim 1 which further comprises a strain gauge on said torsion rod for monitoring the stressing thereof. 
     
     
       13. A picking mechanism as set forth in claim 1 which further comprises a casing having said intermediate member and said lever housed therein said casing having a wall defining said stationary surface. 
     
     
       14. A method of operating a picking mechanism in a projectile loom, said method comprising the steps of turning a torsion rod connected with a picking lever about a longitudinal axis thereof from a zero position to affect picking of a projectile; and   adjusting said zero position of the rod stepwise directly after each picking of a projectile wherein the zero position to increase stressing of the rod is adjusted immediately before a planned interruption of operation.